Liquid crystals can help reject laser pointer attacks on planes

-inch squares of glass scattering of green and blue light on the wall when the cells are triggered by laser illumination (right panels). Posted by Daniel Maurer

Sighting a laser beam to an airplane is not a harmless trick: a sudden flash of bright light can disable the pilot, risking the lives of passengers and crew. But since attacks can occur with different colored lasers, such as red, green, or even blue, it was difficult for scientists to develop a single method to prevent all wavelengths of laser light. Today, researchers report liquid crystals that could ever be included in the windscreen of an airplane to block any color of bright, focused light.

Researchers present their results today at the National Symposium and Exposition of the American Chemical Society (ACS) Spring of 2019.

According to the Federal Aviation Administration, in 2017, there were registered 6754 laser strokes on planes. staff at the Department of Aerospace of our University about the growing problem that occurs at airports around the world, where people were shooting lasers during take-off and landing, in critical phases of flight, "says Dr. Jason Kelecher, project director of the researcher. Such attacks, which cause bright light flares in the cabin, can distract pilots or cause temporary or permanent visual damage, depending on the wavelength and intensity of the laser.

requires that we completely reconstruct the aircraft windshield, but instead add a layer to the glass that uses the existing power system to defrost windscreens, says Daniel Maurer, a student. Kelher and Maurer are at Lewis University.

Instead of being integrated into the windshield, previous approaches included windscreen goggles or glasses that pilots pick up during take-off and landing. However, they may be awkward as they require that the crew carry out such precautionary measures, whether they are objective. An even bigger problem is that these strategies work only for certain wavelengths of laser light. "They do not block everything," says Maurer. "They are usually aimed at green lasers, because they are used for most attacks."

To develop their new approach, researchers used liquid crystals – materials with properties between liquids and solid crystals that make them useful in electronic displays. The team placed a solution of liquid crystals called – (4-methoxybenzylidene) -4-butylaniline (MBBA) between two 1-inch square-shaped glasses. MBBA has a transparent liquid phase and an opaque crystalline phase that scatters light. By applying the voltage on the apparatus, the researchers forced the crystals to align with the electric field and undergone a phase transition in a more solid crystalline state

Aligned crystals blocked up to 95% of red, blue and green beams, through a combination of light scattering, laser energy absorption, and cross-polarization. Liquid crystals could block lasers of different capacities, simulating different distances of illumination, as well as the light that shone at different angles on the glass.

In addition, the system was fully automated: the photoresistor detected laser light and then worked the system of supplying voltage. When the beam was removed, the system switched off the power, and the liquid crystals turned to their transparent, liquid state. "We just want to block the place where the laser enters the windshield, and then it will quickly return to normal after the laser disappears," says Keelher. The rest of the windscreen, which did not hit the laser, would remain transparent at all times.

Now that researchers have shown that their approach is working, they plan to enlarge it from 1-inch squares to the size of the entire windscreen of the aircraft. Initial results have shown that an exemplary sensor on 2-inch squares of the glass will react only to the illuminated area of ​​glass. The team also tests different types of liquid crystals to find even more efficient and versatile ones that quickly return to the transparent state after laser removal.
The new phenomenon has revealed that it fixes the general problem in lasers: the splitting of the wavelength

Additional information:
Analyzing the molecular structure of liquid crystals for the development of independent wavelength films for the removal of laser airborne attacks, the American Chemical Association (ACS) Spring 2019 National Meeting and Exposition.

Provided
American Chemical Society

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Liquid crystals can help counter laser pointer attacks on planes (2019, March 31)
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